Engine control methods are known which utilize a humidity sensor, such as: U.S. Pat. No. 6,575,148.
The inventor herein has recognized a disadvantage with such approaches. Specifically, if the humidity sensor degrades, the engine can operate in regions that produce degraded performance, such as engine misfires, if the engine routines incorrectly presume the humidity is lower than the actual humidity of the ambient air.
Furthermore, the inventor of the subject application has recognized that the engine control sensors typically available fail to provide enough useful information to infer humidity.